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Old 06-25-2008, 01:52 PM   #9 (permalink)
MechEngVT
Mechanical Engineer
 
Join Date: Jun 2008
Location: Richmond, VA
Posts: 190

The Truck - '02 Dodge Ram 1500 SLT Sport
90 day: 13.32 mpg (US)

The Van 2 - '06 Honda Odyssey EX
90 day: 20.56 mpg (US)

GoKart - '14 Hyundai Elantra GT base 6MT
90 day: 30.18 mpg (US)

Godzilla - '21 Ford F350 XL
90 day: 8.69 mpg (US)
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Quote:
Originally Posted by LostCause View Post
High octane fuels will only increase the performace of your cash turning into trash.
I agree with your assessment but your reasoning is more than a bit off-base. Gasoline is a mixture of refined petroleum products that likely includes but is not composed entirely of "octane" (2,2,4 trimethylpentane). The octane rating, or anti-knock index, is merely an indication of how the particular blend of gasoline performs as a ratio of 2,2,4 trimethylpentane (arbitrarily 100 octane rating) and n-heptane (arbitrarily 0 octane rating) in a standard reference engine.

Different octane-rating gasolines are achieved by refining petroleum to produce a different blend of hydrocarbons. Long-chain hydrocarbons have a lower octane rating than short-chain hydrocarbons, so higher octane gasoline can be catalyst-cracked or blended from different distillate outputs, but by and large ethanol is not the primary means of increasing the octane rating. Because of this, it is not generally true that higher octane fuels contain less energy per unit measure.

That said, it is true that higher octane gas will only improve performance if your engine is designed for it, specifically higher compression ratio or forced induction or low-overlap camshaft designs.
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